There are two basic types of carbonation, natural and artificial. One pertinent means of natural carbonation depends upon the action of fermenting yeasts upon residual sugar in solution. Yeast, in the presence of sugar, produces alcohol and carbon dioxide as end products of the fermentation process. In order to obtain natural yeast action carbonation, an appropriate amount of fermentable sugar is placed within the fixed volume of a container along with the yeast-beverage solution. After secure capping, the pressure increases in direct proportion to the rate of fermentation which is further dependent upon factors such as the amount of available fermentable sugar, relative proportion of yeast to sugar, temperature, and time.
Natural carbonation has the advantage of being done in situ or in the same container from which the contents are served to the consumer and has the advantage of eliminating the transfer of carbonated liquid and the consequent loss of carbonation during transfer. But the natural carbonation process described inherently has variances in carbonation level because of the several variables noted above. Another disadvantage is the length of time it takes for natural carbonation. As much as two weeks must be allowed for the beverage to adequately carbonate and settle yeast sediment. Additionally, the said natural carbonation process invariably includes air in the headspace and corresponding detrimental effects of oxygen, flavor loss and improper carbonation pressure; and any coincidental production of alcohol may be undesirable in soft drink formulations. Beverages such as soda water, club soda, quinine water, and carbonated mineral waters cannot be made by natural carbonation because there is no sugar in their recipes.
Artificial carbonation is achieved by introducing carbon dioxide gas into liquid within a fixed volume container under pressure. The gas diffuses rapidly into the liquid under adequate pressure and cool temperatures. But the withdrawal of carbonated liquid from a fixed volume container decreases the carbon dioxide pressure within the carbonated liquid remaining in the container in proportion to the volume of liquid withdrawn.
Some prior art devices compensate for the loss of carbon dioxide pressure when carbonated liquid is withdrawn from the container by introducing additional carbon dioxide under pressure into the fixed volume container in direct proportion to the loss of carbon dioxide pressure occasioned by the withdrawal of carbonated liquid from the container. Other prior art devices attempt restoration of carbon dioxide without regulation.
Some prior art carbonating devices include a diaphragm or air bag in their structure but to applicant's knowledge no prior art device uses a diaphragm or air bag as a principle in carbonation, or in combination with an air pump and relief valves to induce or to maintain a uniform pressure after carbonated liquid is withdrawn. The following disclosures show the state of the art known to applicant regarding the use of diaphragms or air bags in carbonation devices: U.S. Pat. No. 978,103, issued Dec. 6, 1910 to Charles L. Bastion, U.S. Pat. No. 935,698 issued Oct. 5, 1909 to Lewis Silberschmidt, British Pat. No. 11,914 of 1912 to Koenig and Stahl, Swedish Pat. No. 27,648 issued Aug. 24, 1907 to O. E. Ohlsson, and Danish Pat. No. 52,417 issued Dec. 7, 1936 to Hans Andvig and Johannes Freng.